CN114578556A

CN114578556A - Head-up display for mitigating solar loading and back-reflection

Info

Publication number: CN114578556A
Application number: CN202110522271.3A
Authority: CN
Inventors: T·A·塞德; K-H·常; S·考希克; L·G·菲利斯; G·N·肯纳利
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2020-11-30
Filing date: 2021-05-13
Publication date: 2022-06-03
Also published as: US20220171185A1; DE102021114088A1

Abstract

Head-up displays for reducing solar loading and back reflection. Head-up display for a vehicle. The heads-up display includes an image generation unit configured to project an image onto a glass surface and an optical stack. The optical stack includes an infrared reflective wave plate and a dual brightness enhancement film. The infrared reflective wave plate converts incident solar beams from unpolarized light to incident polarized light having an incident S-polarized component and an incident P-polarized component. The dual brightness enhancement film receives incident polarized light from the infrared reflective wave plate and eliminates substantially all of the incident P-polarized component. The dual brightness enhancement film transmits substantially all of the incident S-polarized component.

Description

Head-up display for reducing solar load and back reflection

Technical Field

The present invention relates to a heads-up display for reducing solar loading and back reflection.

Background

The information provided in this section is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

The present disclosure relates to head-up displays (HUDs) that display information on a glass screen, such as the windshield of a motor vehicle (e.g., car, truck), train, airplane, boat, etc. In a heads-up display with high magnification optics, an excessive solar load (solar load) can be projected into the image generation unit (PGU) of the HUD and cause damage to the material. Furthermore, as sunlight enters the optical path of the HUD, the back-reflected sunlight from the PGU surface may follow the same optical path and be seen by the driver. This back reflection reduces the image contrast.

Disclosure of Invention

The present invention is directed to a head-up display, comprising: i) an image generation unit configured to project an image onto the polarization-preserving diffusive surface; and ii) an optical stack comprising: iii) an infrared reflective wave plate; and iv) dual brightness enhancement films. The infrared reflective wave plate reflects an infrared portion of the first incident solar beam and transmits a second incident solar beam having an S-polarized component and a P-polarized component.

In one embodiment, the dual brightness enhancement film receives the second incident solar beam from the infrared reflective wave plate and reflects substantially all of the P-polarized component of the second incident solar beam.

In another embodiment, the dual brightness enhancement film transmits substantially all of the S-polarized component received from the infrared reflective wave plate as a third incident solar beam having an S-polarized component.

In yet another embodiment, the heads-up display includes a light absorber.

In yet another embodiment, the dual brightness enhancement film reflects substantially all of the P-polarized component by deflecting the P-polarized component toward the light absorber.

In further embodiments, the plane of the dual brightness enhancement film is tilted with respect to the direction of the second incident solar beam.

In yet further embodiments, the heads-up display further includes a polarization protection diffuser configured to receive the third incident solar beam having the S-polarized component from the dual brightness enhancement film and transmit the first exit beam having the S-polarized component and the P-polarized component.

In still further embodiments, the S-polarized component of the first exit beam is significantly larger than the P-polarized component of the first exit beam.

In one embodiment, a dual brightness enhancement film receives the first exit beam from the polarization shielding diffuser and eliminates substantially all of the P-polarized component of the first exit beam.

In another embodiment, the dual brightness enhancement film transmits substantially all of the S-polarized component of the first exit beam as the second exit beam.

In yet another embodiment, the dual brightness enhancement film eliminates substantially all of the P-polarized component of the first exit light beam by deflecting the P-polarized component of the first exit light beam toward the light absorber.

In yet another embodiment, the infrared reflective wave plate receives the second exit beam from the dual brightness enhancement film and transmits a third exit beam having an S-polarized component and a P-polarized component.

In a further embodiment, the S-polarized component of the third exit beam is significantly larger than the P-polarized component of the third exit beam.

It is an object of the present invention to provide a method of reducing solar load in a heads-up display comprising an image generation unit configured to project an image onto a polarization protected diffusing surface. The method includes, in an optical stack including an infrared-reflective wave plate and a dual brightness enhancement film: i) reflecting an infrared portion of the first incident solar beam by an infrared-reflecting wave plate; and ii) transmitting, by the infrared reflective wave plate, a second incident solar beam having an S-polarized component and a P-polarized component.

In one embodiment, the method further comprises: i) receiving, in the dual brightness enhancement film, a second incident solar beam from the infrared reflective wave plate; and ii) in the dual brightness enhancement film, reflecting substantially all of the P-polarized component of the second incident light beam.

In another embodiment, the method further comprises, in the dual brightness enhancement film, transmitting a third incident solar beam having an S-polarized component that includes substantially all of the S-polarized component of the second incident solar beam received from the infrared-reflective wave plate.

In yet another embodiment, reflecting substantially all of the P-polarized component of the second incident light beam in the dual brightness enhancement film includes deflecting the P-polarized component toward a light absorber of the heads-up display.

In yet another embodiment, further comprising, in the polarization protective diffuser, receiving a third incident solar beam having an S-polarized component from the dual brightness enhancement film and transmitting a first exit beam having an S-polarized component and a P-polarized component.

Further areas of applicability of the present disclosure will become apparent from the detailed description, claims and drawings. The detailed description and the detailed examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

The invention also provides the following technical scheme:

1. a heads-up display comprising:

an image generation unit configured to project an image onto the polarization-protected diffusive surface; and

an optical stack, comprising:

an infrared reflective wave plate; and

a dual brightness enhancement film having a first brightness enhancement layer,

wherein the infrared reflective wave plate reflects an infrared portion of the first incident solar beam and transmits a second incident solar beam having an S-polarized component and a P-polarized component.

2. The heads-up display of claim 1 wherein the dual brightness enhancement film receives the second incident solar beam from the infrared reflective waveplate and reflects substantially all of the P-polarized component of the second incident solar beam.

3. The heads-up display of claim 2 wherein the dual brightness enhancement film transmits substantially all of the S-polarized component received from the infrared reflective wave plate as a third incident solar beam having an S-polarized component.

4. The heads-up display of claim 3 wherein the heads-up display includes a light absorber.

5. The heads-up display of claim 4 wherein the dual brightness enhancement film reflects substantially all of the P-polarized component by deflecting the P-polarized component toward the light absorber.

6. The heads-up display of claim 5 wherein the plane of the dual brightness enhancement film is tilted with respect to the direction of the second incident solar beam.

7. The heads-up display of claim 6 further comprising a polarization shield diffuser configured to receive the third incident solar beam having the S-polarized component from the dual brightness enhancement film and transmit a first exit beam having an S-polarized component and a P-polarized component.

8. The heads-up display of claim 7 wherein the S-polarized component of the first exit beam is substantially larger than the P-polarized component of the first exit beam.

9. The heads-up display of claim 8 wherein the dual brightness enhancement film receives the first exit beam from the polarization shielding diffuser and eliminates substantially all of the P-polarized component of the first exit beam.

10. The heads-up display of claim 9 wherein the dual brightness enhancement film transmits substantially all of the S-polarized component of the first exit beam as a second exit beam.

11. The heads-up display of claim 10 wherein the dual brightness enhancement film eliminates substantially all of the P-polarized component of the first exit beam by deflecting the P-polarized component of the first exit beam toward the light absorber.

12. The heads-up display of claim 11 wherein the infrared reflective waveplate receives the second exit beam from the dual brightness enhancement film and transmits a third exit beam having an S-polarized component and a P-polarized component.

13. The heads-up display of claim 12 wherein the S-polarized component of the third exit beam is substantially greater than the P-polarized component of the third exit beam.

14. A method of reducing solar loading in a heads-up display including an image generation unit configured to project an image onto a polarization protected diffuse surface, the method comprising:

in an optical stack comprising an infrared-reflective wave plate and a dual brightness enhancement film:

reflecting, by the infrared-reflecting wave plate, an infrared portion of a first incident solar beam; and is

Transmitting, by the infrared reflective wave plate, a second incident solar beam having an S-polarized component and a P-polarized component.

15. The method of aspect 14, further comprising:

receiving, in the dual brightness enhancement film, the second incident solar beam from the infrared reflective wave plate; and is

In the dual brightness enhancement film, substantially all of the P-polarized component of the second incident light beam is reflected.

16. The method of aspect 15, further comprising:

in the dual brightness enhancement film, a third incident solar beam having an S-polarized component is transmitted, the third incident beam including substantially all of the S-polarized component of the second incident solar beam received from the infrared-reflective wave plate.

17. The method of claim 16, wherein reflecting substantially all of the P-polarized component of the second incident light beam in the dual brightness enhancement film comprises deflecting the P-polarized component toward a light absorber of the heads-up display.

18. The method of claim 17, wherein the plane of the dual brightness enhancement film is tilted with respect to the direction of the second incident solar beam.

19. The method of aspect 18, further comprising:

in a polarization-protected diffuser:

receiving the third incident solar beam having the S-polarized component from the dual brightness enhancement film; and is

A first exit beam having S-polarized and P-polarized components is transmitted.

20. The method of claim 19, wherein the S-polarized component of the first exit beam is substantially greater than the P-polarized component of the first exit beam.

Drawings

The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1 is a functional block diagram of an exemplary vehicle system including a heads-up display (HUD) according to an embodiment of the present disclosure.

Fig. 2 is a block diagram of an exemplary HUD illustrating the operation of the HUD according to an embodiment of the present disclosure.

Fig. 3 illustrates the light path of model sunlight reaching the diffuser of a HUD according to an embodiment of the present disclosure.

Fig. 4 illustrates the back reflection reduction of an exemplary HUD according to embodiments of the present disclosure.

Fig. 5 illustrates a light loss analysis of an exemplary HUD according to embodiments of the present disclosure.

In the drawings, reference numbers may be reused to identify similar and/or identical elements.

Detailed Description

The present disclosure describes a heads-up display (HUD) that includes a novel compact optical stack that combines both polarization-selective features, wavelength-selective components, and appropriate mounting angles to mitigate the risk of solar damage on the diffuser of the HUD. The same optical stack is effective for reducing back reflection and improving image contrast. The polarization and wavelength selective component reduces the solar load on the diffuser at the PGU image plane and reduces the back reflection of sunlight from the diffuser that can enter the driver's eyes.

For high magnification HUD designs, the novel optical stack mitigates excessive diffuser temperature and back reflection caused by solar loading. A typical HUD with a magnification of M =6 or less may not suffer from these problems. However, these problems occur if the magnification is increased significantly to reduce the volume of the HUD. The disclosed HUD uses a unique configuration of components to minimize solar loading and back reflection at high magnification to achieve certain goals.

First, the HUD reflects the S-polarization and P-polarization of infrared radiation to the safety absorber using a multilayer dielectric thin film reflector coated on a wave plate. The disclosed HUD also reflects the P-polarization of visible radiation onto the safety absorber using a tilting member called DBEF, which is a multilayer filter design to transmit the S-polarization and reflect the P-polarization. The two elements achieve safe temperatures even in areas where the sun is intense in summer (e.g., arizona).

The disclosed HUD also achieves high image generating unit (PGU) efficiency via the use of a diffuser that preserves the S polarization of the light transmitted by the PGU, since any P polarization produced at the diffuser will not pass through the tilted DBEF. The S-polarization and the P-polarization are conventional coordinate systems with respect to the plane of incidence. The component of the electric field parallel to this plane is called P (parallel) and the component perpendicular to this plane is called S (from the german word "senkrecht" means "perpendicular"). Polarized light with an electric field along the plane of incidence is denoted as P-polarization, while polarized light with an electric field orthogonal to the plane of incidence is denoted as S-polarization. Because half of the visible light entering the HUD is reflected before reaching the diffuser, and the backscattering of the diffuser is small, relatively little visible light is scattered back into the driver's eyes.

Fig. 1 is a functional block diagram of an exemplary vehicle system 100, the vehicle system 100 including a Heads Up Display (HUD) 190 according to an embodiment of the present disclosure. Although a vehicle system for a manually driven hybrid vehicle is shown and described, the present disclosure is also applicable to autonomously driven and fully electric vehicles that incorporate a heads-up display. The application is also applicable to non-automotive embodiments such as trains, ships and airplanes.

The engine 102 combusts an air/fuel mixture to produce drive torque. An Engine Control Module (ECM) 106 controls the engine 102 based on one or more driver or vehicle inputs. For example, the ECM 106 may control execution of engine actuators, such as a throttle valve, one or more spark plugs, one or more fuel injectors, valve actuators, camshaft phasing regulators, Exhaust Gas Recirculation (EGR) valves, one or more boost devices, and other suitable engine actuators.

The engine 102 may output torque to the transmission 110. A Transmission Control Module (TCM) 114 controls operation of the transmission 110. For example, the TCM 114 may control gear selection and one or more torque-transmitting devices (e.g., torque converters, one or more clutches, etc.) within the transmission 110.

The vehicle system 100 may include one or more electric machines. For example, as shown in the example of fig. 1, the motor 118 may be implemented within the transmission 110. The electric machine may act as a generator or as a motor at a given time. When acting as a generator, the electric machine converts mechanical energy into electrical energy. The electrical energy may charge the battery 126 via a Power Control Device (PCD) 130. When acting as a motor, the electric machine generates torque that supplements or replaces the torque output by the engine 102. Although an example of one electric machine is provided, the vehicle may include zero or more electric machines.

A power inverter control module (PIM) 134 may control the motor 118 and the PCD 130. The PCD 130 applies (e.g., direct current) power from the battery 126 to the (e.g., alternating current) motor 118 based on the signal from the PIM 134, and the PCD 130 provides power output by the motor 118 to, for example, the battery 126. In various embodiments, PIM 134 may be referred to as a Power Inverter Module (PIM).

The steering control module 140 controls steering/turning of the wheels of the vehicle, for example, based on the driver turning the steering wheel in the vehicle and/or steering commands from one or more vehicle control modules. A steering wheel angle Sensor (SWA) monitors the rotational position of the steering wheel and generates a SWA 142 signal based on the position of the steering wheel. As an example, the steering control module 140 may control vehicle steering via the EPS motor 144 based on the SWA 142 signal. However, the vehicle may include another type of steering system. An Electronic Brake Control Module (EBCM) 150 may selectively control the brakes 154 of the vehicle.

The modules of the vehicle may share parameters via a Controller Area Network (CAN) 162. CAN 162 may also be referred to as a vehicle area network. For example, CAN 162 may include one or more data buses. Various parameters are made available to other control modules by a given control module via CAN 162.

The driver inputs may include, for example, an Accelerator Pedal Position (APP) 166 that may be provided to the ECM 106. A Brake Pedal Position (BPP) 170 may be provided to the EBCM 150. Park, reverse, neutral, drive rod (PRNDL) positions 174 may be provided to the TCM 114. The ignition status 178 may be provided to a Body Control Module (BCM) 180. For example, the ignition status 178 may be input by the driver via an ignition key, a button, or a switch. At a given time, the ignition state 178 may be one of off, assisted, running, or crank (crank).

According to an exemplary embodiment of the present disclosure, the vehicle system 100 further comprises an advanced computing module 185 and a Heads Up Display (HUD) 190. As will be explained in greater detail below, HUD 190 also includes a window (or lens) 191 through which light is projected onto a windshield (not shown) of vehicle system 100.

The advanced computing module 185 includes a high performance computing platform that controls many of the higher-order and lower-order functions of the vehicle system 100. In a typical implementation, the advanced computing module 185 may be implemented as a microprocessor and associated memory. The advanced computing module 185 executes a kernel that controls the overall operation of the advanced computing module 185.

In accordance with the principles of the present disclosure, the advanced computing module 185 consumes sensor information from various sensors (not shown) in the vehicle system 100. The sensor information may include, for example, vehicle speed data, steering wheel angle sensor data, brake status data, LiDAR system data, radar data, camera images, GPS data, accelerometer data, engine temperature and RPM, and the like, to determine the speed, direction, and location of the vehicle system 100.

The advanced computing module 185 processes selected portions of the sensor information to generate useful information for display on the windshield via the HUD 190. For example, the advanced calculation module 185 may send vehicle speed, engine RPM, engine temperature, fuel status, navigation directions, etc. to the HUD 190, which the HUD 190 then projects onto the inner surface of the windshield. This enables the driver to view the projected information while looking forward. The driver does not need to look down at the dashboard in order to view the projected information, thus removing his or her eyes from the road.

FIG. 2 is a block diagram of an exemplary HUD 190 illustrating the operation of HUD 190 according to an embodiment of the present disclosure. HUD 190 includes a lens 191 that allows light to enter and exit the housing of HUD 190. The internal components of HUD 190 include an image generation unit 215, a polarization shield diffuser 225, a Dual Brightness Enhancement Film (DBEF) 230, an Infrared (IR) reflective wave plate 235, a mirror 220, and a light absorber 240.

DBEF 230 is a thin multilayer reflective polarizer that includes two diffusing surfaces to provide brightness enhancement and high visual quality. The IR reflecting waveplate 235 (also referred to as a retarder) transmits light and changes its polarization state without attenuating, deflecting, or shifting the light beam. The IR reflecting waveplate 235 accomplishes this by retarding (or retarding) one component of polarization (e.g., S polarization) relative to its orthogonal component (e.g., P polarization).

Fig. 2 shows two optical paths. The first light path 205 includes an incident solar beam from the sun 201 that passes through the windshield 202 of the vehicle system 100, enters the lens 191 of the HUD 190, reflects from the mirror 220, passes through the Infrared (IR) reflective wavelength plate 235, and reflects from the DBEF 230 toward the light absorber 240. The boundaries of the first light path 205 are indicated by lines with similarly sized stubs. Some of the incident solar beams may still pass through the polarization shielding diffuser 225 before entering the PGU 215.

The second light path 210 is an image projected from the PGU unit 215, which passes through a polarization protection diffuser 225, DBEF 230, and IR reflecting waveplate 235 before being reflected by mirror 220 onto the windshield 202 through lens 191. The windshield 202 also reflects the PGU light into an eye box (eyebox) 203, which eye box 203 represents the area of the driver's eyes. Lines with alternating dots and dashes indicate the boundaries of the second light path 210. The cross fill pattern further distinguishes the second light path 210 from the first light path 205.

Note that the

light paths

205 and 210 are substantially perpendicular to the plane of the polarization shielding diffuser 225 and the IR reflecting waveplate 235. However, the plane of the DBEF 230 is tilted with respect to the first light path 205 and the second light path 210 such that the

light paths

205 and 210 are not perpendicular to the plane of the DBEF 230.

Fig. 3 illustrates the light path of model sunlight reaching the diffuser of HUD 190 according to an embodiment of the present disclosure. Light segment 301-305 represents an incident solar beam. An incident solar beam from the sun 201 enters the windshield as a light path section 301. Light path section 301 passes through windshield 202 and may experience some PVB and Fresnel loss (Fresnel loss) to become light path section 302. Light path segment 302 reflects from mirror 220 and may experience some glare capture lens loss to become light path segment 303. Lightpath segment 303 then passes through IR reflective waveplate 235 where additional losses may be experienced and become lightpath segment 304.

Unpolarized IR light in optical path segment 303 is polarized in optical path segment 304 by IR reflecting wave plate 235 into 50% S polarized light and 50% P polarized light. Lightpath segment 304 then passes through DBEF 230 and becomes lightpath segment 305. In the optical path segment 305, the DBEF 230 reduces almost all of the P-polarized luminance of the optical path segment 304 and also reduces some of the S-polarized luminance. The polarization shielding diffuser 225 then partially absorbs the light segments 305. With the optical stack, the temperature of the diffuser after absorbing the light path segment 305 is well controlled to a temperature below the glass transition temperature of the diffuser material.

Fig. 4 illustrates the back reflection reduction of an exemplary HUD 190 according to embodiments of the present disclosure. Light segment 301-303 and

light segments

404 and 405 represent incident solar beams from the sun 201. The

light segments

301 and 303 are the same as in fig. 3. The IR reflecting waveplate 235 reflects the infrared component 403 of the incident solar beam. IR reflecting waveplate 235 converts unpolarized light in optical path segment 303 to polarized light in optical path segment 404 that includes a 50% S-polarized luminance and a 50% P-polarized luminance. However, after passing through the DBEF 230, the optical path segment 405 includes only S-polarized light.

Polarization protection diffuser 225 reflects about 5% of the light in light path segment 405 back toward windshield 202 in light path segment 451. For example, the polarization shield diffuser 225 reflects the light path segment 451 back as 70% S-polarized luminance and 30% P-polarized luminance. The DBEF 230 is angled to reflect the P-polarization in the optical path segment 462 toward the light absorber 240. However, the DBEF 230 transmits the S-polarized light in the optical path segment 452 toward the IR reflective waveplate 235. The IR reflecting waveplate 235 then converts the 100% S polarized light in optical path segment 452 into optical path segment 453 (25% P polarized luminance) and optical path segment 463 (75% S polarized luminance).

The mirror 220 reflects approximately 100% of the light path segment 453 as the

light path segment

454 and 100% of the light path segment 463 as the light path segment 464 to the windshield 202. Windshield 202 then reflects approximately 3% of the P-polarized luminance in light segment 454 as light segment 455. Windshield 202 also reflects approximately 20% of the brightness of the S polarization in light path segment 464 as light path segment 465. Windshield 202 reflects

light segments

455 and 465 toward eyebox 203.

Without the DBEF 230 and the IR reflecting waveplate 235, back reflections from a conventional diffuser (e.g., reflecting 8% of unpolarized light) can produce 325.1 cd/m at the eye box 203²The reflected brightness of (1). However, since the disclosed HUD 190 includes a novel combination of a polarization shielding diffuser 225, a tilted DBEF 230, and an IR reflecting waveplate 235, the reflected brightness at the eye box 203 can be reduced to 219.1 cd/m². This represents a 32.6% reduction in back-reflected light.

Fig. 5 illustrates an optical loss analysis of an exemplary HUD 190 according to embodiments of the present disclosure. The light segment 501-506 represents the light of the image projected from the PGU 215 to the eye box 203. Projected light from PGU 215 is incident on polarization-shielding diffuser 225 as light path segment 501. Assume that lightpath segment 501 has a cd 75,000/m²Brightness and 100% S polarization. Polarization-shielding diffuser 225 creates a light path segment 502, which can have, for example, 5% P polarization and 95% S polarization.

DBEF 230 eliminates P-polarization from optical path segment 502 and transmits optical segment 503 with 100% S-polarization toward IR reflecting waveplate 235. IR reflecting waveplate 235 then rotates the 100% S polarized light in optical path segment 503 into optical path segment 504, which optical path segment 504 may include 25% P polarized luminance and 75% S polarized luminance. The mirror 220 reflects 100% of the light path segment 504 as light path segment 505, which light path segment 505 is transmitted to the windshield 202. Finally, the windshield 202 reflects the light path segment 505 as a light path segment 506, which light path segment 506 is transmitted to the eyebox 203. Lightpath segment 506 may include 20% S-polarization luminance and 3% P-polarization luminance.

In this manner, the eye box 203 reception may have a cd/m of 75,000²The initial lightpath segment 501 of exemplary luminance as lightpath segment 506, the lightpath segment 506 may have 9,455.6 cd/m²S polarization luminance sum of 472.8 cd/m²P-polarized luminance of (1). The combined brightness of the S-polarized and P-polarized light is 9,928.4 cd/m²。

In the lower half of fig. 5, light loss is present based on the assumption that diffuser 530 is not a polarization-shielding diffuser, and that there are no DBEF 230 and IR reflecting waveplates 235 in the optical stack. A conventional diffuser 530. Projected light from PGU 215 is incident on conventional diffuser 530 as light path segment 511. As before, assume lightpath segment 511 has a 75,000 cd/m²Brightness and 100% S polarization. The diffuser 530 creates a light path segment 512, which may have, for example, 30% P polarization and 70% S polarization. The mirror 220 reflects 100% of the optical path segment 512 as the optical path segment 515, the optical path segment 515 being transmitted to the windshield 202. Windshield 202 reflects light section 515 as light section 516, the optical path segment 516 is transmitted to the eye box 203. Optical segment 516 may include 20% S polarized light and 3% P polarized light.

In this manner, the eye box 203 reception may have a cd/m of 75,000²The initial lightpath segment 511 of exemplary luminance as lightpath segment 516, the lightpath segment 516 may have a 10,500 cd/m²S polarization luminance of (1) and 675 cd/m²P-polarized luminance of (1). The combined brightness of the S-polarized and P-polarized light is 11,175 cd/m²。

Thus, the optical stack at the top of fig. 5, which includes polarization preserving diffuser 225, DBEF 230, and IR reflecting waveplate 235, can cause a brightness loss of 11% (i.e., 99.284.40 cd/m)²Relative to 11.175 cd/m²). However, this is still close to the target luminance of 10,000 cd/m for HUD 190²。

The foregoing description is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims. It should be understood that one or more steps of the method may be performed in a different order (or simultaneously) without altering the principles of the present disclosure. Moreover, although each of the embodiments is described above as having certain features, any one or more of those features described with respect to any embodiment of the present disclosure may be implemented in and/or combined with the features of any other embodiment, even if the combination is not explicitly described. In other words, the described embodiments are not mutually exclusive and the mutual arrangement of one or more embodiments is still within the scope of the present disclosure. It should also be understood that steps in the embodiments may also be omitted. For example, all route-based evaluations and actions may be cancelled, such that only instability and possible occupancy are monitored and actions are taken on that basis.

Various terms are used to describe the spatial and functional relationships between elements (e.g., between modules, circuit elements, semiconductor layers, etc.), including "connected," joined, "" coupled, "" adjacent, "" above … …, "" above … …, "" below … …, "and" disposed. Unless explicitly described as "direct", when a relationship between a first element and a second element is described in the above disclosure, the relationship may be a direct relationship in which there is no other intervening element between the first element and the second element, but may also be an indirect relationship in which there is one or more intervening elements (spatially or functionally) between the first element and the second element. As used herein, at least one of the phrases A, B and C should be construed to mean logic (a OR B OR C) using non-exclusive logic "OR (OR)", and should not be construed to mean "at least one of a, at least one of B, and at least one of C".

In the drawings, the direction of arrows, as indicated by the arrows, generally indicate the flow of information (e.g., data or instructions) of interest illustrated. For example, when component A and component B exchange various information, but the information communicated from component A to component B is associated with a graphical representation, an arrow may point from component A to component B. The one-way arrow does not imply that there is no other information to be transferred from element B to element a. Further, for information sent from element a to element B, element B may send a request for information or send an acknowledgement of receipt of information to element a.

In this application, including the definitions below, the term "module" or the term "controller" may be replaced with the term "circuit". The term "module" may refer to, may be part of, or may include the following: an Application Specific Integrated Circuit (ASIC); digital, analog, or hybrid analog/digital discrete circuits; digital, analog, or hybrid analog/digital integrated circuits; a combinational logic circuit; a Field Programmable Gate Array (FPGA); processor circuitry (shared, dedicated, or group) that executes code; memory circuitry (shared, dedicated, or group) that stores code executed by the processor circuitry; other suitable hardware components that provide the described functionality; or a combination of some or all of the above, such as in a system on a chip.

The module may include one or more interface circuits. In some examples, the interface circuit may include a wired interface or a wireless interface to a Local Area Network (LAN), the internet, a Wide Area Network (WAN), or a combination thereof. The functionality of any given module of the present disclosure may be distributed among multiple modules connected via interface circuits. For example, multiple modules may implement load balancing. In further examples, a server (also referred to as a remote, or cloud) module may implement some functionality on behalf of a client module.

The term code, as used above, may include software, firmware, and/or microcode, and may refer to programs, routines, functions, classes, data structures, and/or objects. The term "shared processor circuit" encompasses a single processor circuit that executes some or all code from multiple modules. The term "set of processor circuits" includes processor circuits that execute some or all code from one or more modules in combination with additional processor circuits. References to multiple processor circuits include multiple processor circuits on separate dies, multiple processor circuits on a single die, multiple cores of a single processor circuit, multiple threads of a single processor circuit, or a combination of the above. The term "shared memory circuit" encompasses a single memory circuit that stores some or all code from multiple modules. The term "bank memory circuit" includes memory circuits that store some or all code from one or more modules in combination with additional memory.

The term "memory circuit" is a subset of the term "computer-readable medium". As used herein, the term "computer-readable medium" does not include transitory electrical or electromagnetic signals propagating through a medium (e.g., on a carrier wave), and thus, the term "computer-readable medium" may be considered tangible and non-transitory. Non-limiting examples of a non-transitory tangible computer-readable medium are a non-volatile memory circuit (such as a flash memory circuit, an erasable programmable read-only memory circuit, or a mask read-only memory circuit), a volatile memory circuit (such as a static random access memory circuit, or a dynamic random access memory circuit), a magnetic storage medium (such as an analog or digital tape, or a hard drive), and an optical storage medium (such as a CD, DVD, or blu-ray disc).

The apparatus and methods described herein may be partially or completely implemented by a special purpose computer, which results from configuring a general purpose computer to perform one or more particular functions embodied in a computer program. The functional blocks, flowchart components, and other elements described above are used as software descriptions that can be compiled into a computer program by a skilled person or programmer with the routine work.

The computer program includes processor-executable instructions stored on at least one non-transitory tangible computer-readable medium. The computer program may also comprise or rely on stored data. The computer programs may include a basic input/output system (BIOS) that interacts with the hardware of the special purpose computer, a device driver that interacts with specific devices of the special purpose computer, one or more operating systems, user applications, background services, background applications, and the like.

The computer program may include: (i) descriptive text to be parsed, such as HTML (hypertext markup language), XML (extensible markup language), or JSON (JavaScript object notation); (ii) assembling the code; (iii) object code generated by a compiler from source code; (iv) source code for execution by an interpreter; (v) source code for compilation and execution by a just-in-time compiler, and the like. By way of example only, the source code may be written using syntax from the following languages, including: C. c + +, C #, Objective-C, Swift, Haskell, Go, SQL, R, Lisp, Java, Fortran, Perl, Pascal, Curl, OCaml, Javascript, HTML5 (fifth edition of Hypertext markup language), Ada, ASP (dynamic Server pages), PHP (PHP: Hypertext preprocessor), Scala, Eiffel, Smalltalk, Erlang, Ruby, Flash, Visual Basic, Lua, MATLAB, SIMULINK, and Python.

Claims

1. A heads-up display comprising:

an optical stack, comprising:

an infrared reflective wave plate; and

a dual brightness enhancement film having a first brightness enhancement layer,

2. The heads-up display of claim 1 wherein the dual brightness enhancement film receives the second incident solar beam from the infrared reflective wave plate and reflects substantially all of the P-polarized component of the second incident solar beam.

10. A method of reducing solar loading in a heads-up display including an image generation unit configured to project an image onto a polarization protected diffuse surface, the method comprising: